Trouble No. 1 - Blinking Overdrive Light While Driving

NOTE:
^ If diagnostic code Nos. 21, 22, 23, 31, 32, 33 or 34 occur, the overdrive off indicator light will begin to blink immediately to warn the driver. However, an impact or shock may cause the blinking to stop; but the code will still be retained in the ECT computer memory until canceled out.
^ In the event of a simultaneous malfunction of both No. 1 and No. 2 speed sensors, no diagnostic code will appear and the fail-safe system will not function. However, when driving in the "D" range, the transmission will not upshift from first gear, regardless of the vehicle speed.

Trouble No. 1 Blinking Overdrive Indicator Light (While Driving)